Users who are less aware of how the NL() function works may define multiple NL(Rows) functions adjacent to one another, which will not only likely break the report, but take a very long time to run before realizing a mistake has been made. 

Jet Reports can help the user avoid this mistake by detecting when a second NL(Rows) function is defined adjacent to another NL(Rows) function to show a warning modal asking "You have defined multiple NL(Rows) functions on this sheet, which may cause unexpected results and cause your report to run slowly. Are you sure you want to do this?"